Image copyright The Presidency of the Republic of South AfricaImage caption Atul Gupta (centre) shakes hands with President Jacob Zuma (right) in 2012. Their relationship has come under scrutiny in recent years

South Africa’s elite police unit has raided the home of a controversial business family linked to President Jacob Zuma, as pressure increases on him to stand down.

Officials say three people were arrested as part of an investigation into the wealthy, Indian-born Guptas.

They have been accused of using their close friendship with Mr Zuma to wield enormous political influence.

Meanwhile, Mr Zuma’s party has given him until the end of the day to resign.

His links to the Guptas are one of the reasons he is being forced to resign before the 2019 general election.

That investigation relates to the Estina dairy farm near Vrede, in the Free State, a project which was originally meant to help poor black farmers but from which the Gupta family are alleged to have pocketed millions of dollars, allegations they deny.

A tranche of leaked emails released last year alleged that some of the money ended up paying for the family’s lavish wedding at Sun City, South Africa’s upmarket holiday resort.

In January, the Hawks raided the offices of the Free State Premier, Ace Magashule, looking for documents linked to the project. Mr Magashule was elected secretary-general of the ruling African National Congress (ANC) in December.

Image copyrightEPAImage caption The family’s walled Johannesburg compound was subject to an early morning search by elite police

The chief whip of the opposition Democratic Alliance John Steenhuisen told the BBC the arrests he thought the timing of today’s raid was particularly interesting, given .

“I think the arrests this morning were a warning shot fired across the bows of Mr Zuma’s camp to say that ‘Look if you don’t step down and resign, this could well be happening to you,'” he said.

Just who are the Gupta family?

The embattled Gupta family own a range of business interests in South Africa, including computing, mining, air travel, energy, technology and media.

The three brothers, Atul, Rajesh and Ajay, moved to the country in 1993 from India, just as white-minority rule was ending.

They are known friends of President Zuma – and his son, daughter and one of the president’s wives worked for the family’s firms.

The brothers have been accused of wielding enormous political influence in South Africa, with critics alleging that they have tried to “capture the state” to advance their own business interests

At the scene: Cheers and insults

By Andrew Harding, BBC News, Saxonwold, Johannesburg

Early this morning, as the plush suburb of Saxonwold was waking up – gardeners walking dogs, children being taken to school in 4x4s – armed police arrived at the enormous, high-walled, Gupta compound opposite the lion enclosure of Johannesburg Zoo, sealing off a section of the road, and venturing inside.

Soon afterwards, two luxury vehicles were seen driving out of the gates escorted by police in separate cars.

The Hawks – the elite high-priority crimes unit – confirmed that this was an operation to arrest suspects, rather than to raid properties.

A blue police helicopter swung over the property, as local people voiced satisfaction about the police action.

“It’s very emotional for all South Africans. This is about getting South Africa right again,” said Tessa Turvey.

“This is real meaningful change. I certainly don’t think it would have happened if Zuma was still president of the ANC,” said a man, walking his dogs.

What are the other allegations against the Guptas?

Former Deputy Finance Minister Mcebisi Jonas made a public allegation in 2016 that he was offered 600m rand ($50m; £36m) by the Gupta family to be the next finance minister – as long as he did their bidding.

It was followed by a damning report by a South African government ombudsman that accused the Guptas and President Zuma of colluding to win government contracts.

The public backlash worsened in 2017 when more than 100,000 emails were leaked which appeared to show the extent of the family’s influence.

It suggested a complex web of government contracts, as well as alleged kickbacks and money laundering.

It prompted marches and public protests against the family and President Zuma, dubbed the “Zuptas”.